1. Field of the Invention
The invention concerns a backpack.
2. Background Art
Backpacks are convenient means for the transport of items and are used more and more in daily life. Due to their flexible cover material, backpacks have a low weight and only minimally impede movement of the wearer. Moreover, backpacks can adjust their volume to the transported items due to the flexible material, so that in general an empty backpack occupies less volume than a full backpack.
The flexible material of a backpack, however, also limits its range of applications. Therefore, big backpacks for carrying heavy loads frequently have covers that are provided with a frame to achieve a better distribution of the load on the shoulder and the back. In some constructions, rigid parts of the backpack make sure that the backpack does not directly contact the back of the wearer, in order to promote ventilation of the back and reduce sweating. However, a backpack that includes a frame typically has a higher weight.
A further disadvantage of the flexible cover material of a backpack is that its contents are less protected than in a container made from a rigid material. The flexible material also leads to problems during packing of a backpack, in particular with big and heavy items, since the opening of a backpack is not rigid. For instance, putting a folder into the backpack usually requires a particular handling in order to create an appropriate shape of the opening of the backpack. These problems also arise whenever an item has to be gripped with two hands during packing. In this case, the help of a second person is frequently needed to hold the backpack open.
In order to overcome these disadvantages, U.S. Pat. No. 6,938,761 and U.S. Pat. No. 6,629,629 describe backpacks that have a hard shell made from substantially rigid material. A rigid backpack is, however, inconvenient to carry on the back and has a higher weight than a backpack made of flexible material. In addition, the described backpacks are assembled from several elements, which render their manufacture, handling, and storage more complicated.
Furthermore, U.S. Patent Publication No. 2005/0061844 and U.S. Pat. No. 5,911,348 describe backpacks which consist of a hard shell and a lid which are connected at the bottom side of the backpack. This leads to a large opening, which also does not have to be kept open with the hands. However, the backpack has to be laid down for packing, otherwise its content may drop out.
Given the foregoing, what is needed is a backpack which provides in particular protection of its contents and which can be easily packed.